Lactic acid is an important platform chemical with many applications. Over the last decade, lactic acid has gained importance in the detergence industry. Lactic acid has descaling as well as anti-bacterial properties, so has been used as an environmentally beneficial cleaning product. Furthermore, lactic acid is a precursor for several biodegradable polymers such as polylactic acid. These types of plastics provide a good option for substituting conventional plastics produced from petroleum oil because of low CO2 emissions. Other applications include precursors for lactate esters, which can replace petrochemical derived solvents.
Lactic acid is typically produced by fermentation of carbohydrates such as glucose, fructose and sucrose. The most commercially important genus of lactic acid fermenting bacteria is Lactobacillus, though other bacteria and even yeast are also used. In such fermentations, lactic acid is formed through the reduction of pyruvate, which is in turn produced by glycolysis. The cost of these carbohydrate feed stocks is influenced by their value as human food or animal feed. For example, cultivation of starch or sucrose-producing crops for lactic acid production is not economically sustainable in all geographies. Therefore, it is of interest to develop technologies to convert lower cost and/or more abundant carbon resources into lactic acid.
Carbon Monoxide (CO) is a major by-product of the incomplete combustion of organic materials such as coal or oil and oil derived products. Although the complete combustion of carbon containing precursors yields CO2 and water as the only end products, some industrial processes need elevated temperatures favouring the build up of carbon monoxide over CO2. One example is the steel industry, where high temperatures are needed to generate desired steel qualities. For example, the steel industry in Australia is reported to produce and release into the atmosphere over 500,000 tonnes of CO annually.
Furthermore, CO is also a major component of syngas, where varying amounts of CO and H2 are generated by gasification of a carbon-containing fuel. For example, syngas may be produced by cracking the organic biomass of waste woods and timber to generate precursors for the production of fuels and more complex chemicals.
The release of CO into the atmosphere may have significant environmental impact. In addition, emissions taxes may be required to be paid, increasing costs to industrial plants. Since CO is a reactive energy rich molecule, it can be used as a precursor compound for the production of a variety of chemicals. However, this valuable feedstock has not been utilised to produce lactic acid.
It is an object of the present invention to provide a process that goes at least some way towards overcoming the above disadvantages or at least to provide the public with a useful choice.